Description: (Applicant's Description) The Developmental Therapeutics Program is the keystone of the CCC's effort to discover, develop, understand, and test new chemotherapeutic agents. To achieve this goal the Program is involved in the synthesis and screening of new compounds directed at specific targets as well as the refinement of newly identified compounds. Compounds are initially studied using in vitro systems, animal models, and in Phase I trials. We have developed several new agents that already entered clinical testing or will do so within the next year. A second element of the program involves new approaches to assessing tumor response to chemotherapy, which include studies of drug pharmacokinetics, pharmacodynamics, and the analysis of pathways of drug metabolism and resistance in patient tissue and tumor samples. New, non- invasive imaging approaches, PET and MR, are being developed to measure tumor growth, perfusion, and drug kinetics. Finally, we are validating our new approaches in Phase II and Phase III trials. These are often conducted by our investigators as part of national trials through cooperative groups. Each of these main themes brings clinical and basic science researchers together to produce innovative new therapies and methods of assessment. Investigators in the Breast Cancer, Prostate Cancer, Population Studies and Prevention, and Molecular Biology and Genetics Programs are collaborating in testing new therapeutic approaches with colleagues in Developmental Therapeutics. Over the last few years a large number of new treatments have been introduced to the clinic, and a larger number are in the pipeline. This program aims to speed the assessment of the promise and risks of new therapy to provide patients with the best possible chance at survival.